The present invention relates to a structure of a pivot receiving surface formed at a base so as to support an abutment surface of a pivot assembly disposed in a head supporting mechanism in a magnetic disk drive and, more particularly, to a structure of a pivot receiving surface which may adjust the attitude of a head supporting mechanism.
A head/slider flies above a magnetic disk with a slight clearance (hereinafter referred to as “a flying height”) in a magnetic disk drive. A load beam is attached to a tip of a carriage assembly of a rotary type, and thus, is designed to be rotated above the magnetic disk. To the load beam is attached a flexure, to which the head/slider is fixed in such a manner as to achieve a flexible operation by means of the flexure.
The carriage assembly is provided with a pivot opening, into which a pivot assembly is inserted, at the center thereof. A housing of the pivot assembly and the carriage assembly are integrated by fixing a shaft of the pivot assembly to the base, such that they can be rotated by a voice coil motor (hereinafter abbreviated as “a VCM”). Since a clearance between the load beam and the surface of the magnetic disk markedly influences the flying performance of the head/slider, the clearance needs to fall within a predetermined range at least within a range in which the head/slider flies.
The magnetic disk is disposed in a hub of a spindle motor in such a manner as to be parallel to a predetermined reference surface. Therefore, unless the load beam also must be operated while keeping a predetermined clearance with respect to the same reference surface, the clearance between the load beam and the surface of the magnetic disk is varied according to the position of the magnetic disk, so that the head/slider cannot fly at a stable flying height. Also in the case where the load beam is inclined in a direction perpendicular to the rotating direction of the load beam, the flying performance is degraded.
A surface formed at the base for supporting the pivot assembly is referred to as “a pivot receiving surface” in the present specification. The attitude of the pivot receiving surface determines the attitude of the pivot assembly, and further, the attitude of the pivot assembly determines the attitude of the carriage assembly. Since the load beam is disposed in the carriage assembly, the magnetic disk drive needs to be configured such that the pivot receiving surface takes the correct attitude in order to achieve the correct attitude of the load beam.
In recent years, the flying height of the head/slider has become lower, and further, higher accuracy has been required for the attitude of the load beam for supporting the head/slider with respect to the surface of the magnetic disk. This cannot be satisfactorily coped with by the conventional structure of the pivot receiving surface. Japanese Patent Laid-open No. 2001-28161 discloses the technique of drawing a chassis at three points in order to fix a spindle motor. Japanese Patent Laid-open No. Hei 6-84257 discloses the technique of supporting a disk at three points by the use of a ball in order to clamp the disk with high accuracy. Japanese Utility Model Laid-open No. Sho 64-18422 discloses the technique of supporting an optical head at three points. Japanese Patent Laid-open No. Sho 59-94275 discloses the technique of supporting a disk at three points in order to eliminate a radial clearance between a bearing inner/outer race of a pivot cartridge and a bearing ball.